The invention relates to a method of producing consumable electrodes of large diameters for remelting, in particular electroslag remelting, wherein the electrode is assembled of individual longitudinal parts adjacently arranged.
With the ingot treating and remelting processes used to an increasing extent in the high-grade steel industry, consumable electrodes are in most cases used as insert parts. This involves remelting processes, such as vacuum arc-furnace methods and electroslag remelting processes.
Consumable electrodes for the metallurgical methods mentioned above have hitherto been produced by reshaping a cast ingot into an electrode body by rolling or forging and welding a gripping head for an electrode holding device to the same. Although it is possible in this manner to obtain electrode diameters that, as required, are uniform over the total electrode length, reshaping is time consuming. It is furthermore disadvantageous that, when producing rod-shaped bodies from big cast ingots, the ingot segregation inevitably present in the ingot will be recognizeable even in the electrode to be remelted. In some cases, this segregation may be reflected in the remelted ingot--although to a reduced extent.
A further disadvantage of producing consumable electrodes by casting into common closed-end moulds of steel making plants is that these must have a conical shape in order to be able to draw off the mould after the casting has solidified, and the maximum electrode length will depend on the mould length. The mould length, however, cannot be arbitrarily increased. Moreover, a so-called dead-head has to be provided for casting-technological reasons, which dead head has to be separated from the remaining ingot part, thus constituting a loss of material and additional work.
The tendency in the development of the ingot treating and remelting methods is towards the production of ever increasing ingots, having a round cross section as a rule. It is thus necessary to adapt the electrode to the cross section of the mould used for the ingot treating methods. In order to produce consumable electrodes having larger diameters, it has already been proposed to combine rod-shaped bodies made up of several parts having a cross section that corresponds to part or half of a circular cross section (British Pat. No. 1,001,042). These electrodes which, when seen in cross-section, are multiple-part electrodes, thus have an approximately circular outer contour and for this reason can be produced only with difficulty and great expenditure. Another proposal provides for melting together into one ingot, consumable electrodes that are multiply subdivided in the longitudinal and transverse directions, the individual construction elements having a square cross section which is produced by forging; the outer contour of these electrodes is also square (British Pat. No. 1,002,106). This type of assembled electrode not only is complex and time consuming in its production, it also cannot be used for the production of ingots in circular moulds, which shape is needed because the cross section of the consumable electrode has to be designed such that its surface has a nearly uniform distance from the rim of the mould top part (Austrian Pat. No. 282,845) and from the remelting electrode, respectively.